Synthesis and Evaluation of Thiophene-Based Organic Dyes Contain­ing a Rigid and Nonplanar Donor with Secondary Electron Donors for Use in Dye-Sensitized Solar Cells

We demonstrate herein the divergent synthesis of six dyes containing our originally developed rigid and nonplanar donor with three different secondary electron donors (SEDs), namely thiophene, 4-methoxybenzene, and diphenylethene. Evaluation of the photophysical properties of the synthesized dyes revealed that the introduction of the SEDs resulted in an increased absorbance in the 350-450 nm region. The influence of the SEDs on the electrochemical and photovoltaic properties depended on their structure and position of attachment. The introduction of the thiophene SED to D44A2, which we previously reported to be our best dye, resulted in an increased J(sc). The dye-sensitized solar cell (DSSC) prepared by using dye 2b, which contains the thiophene SED, shows a higher power conversion efficiency (PCE; = 4.62 +/- 0.02%) and a higher incident photon-to-current conversion efficiency (IPCE) in the region 300-600 nm than D4 pi 4A2.